Chap. XIV.] RUDIMENTARY ORGANS. 255 



scendants from some one ancient progenitor, having ap- 

 peared at a not very early period of life, and having been 

 inherited at a corresponding period. Embryology rises 

 greatly in interest, when we look at the embryo as a 

 picture, more or less obscured, of the progenitor, either 

 in its adult or larval state, of all the members of the 

 same great class. 



Rudimentary, Atrophied, and Aborted Organs. 



Organs or parts in this strange condition, bearing the 

 plain stamp of inutility, are extremely common, or even 

 general, throughout nature. It would be impossible to 

 name one of the higher animals in which some part or 

 other is not in a rudimentary condition. In the mam- 

 malia, for instance, the males possess rudimentary mam- 

 mae; in snakes one lobe of the lungs is rudimentary; 

 in birds the " bastard- wing " may safely be considered 

 as a rudimentary digit, and in some species the whole 

 wing is so far rudimentary that it cannot be used for 

 flight. What can be more curious than the presence 

 of teeth in foetal whales, which when grown up have 

 not a tooth in their heads; or the teeth, which never 

 cut through the gums, in the upper jaws of unborn 

 calves? 



Rudimentary organs plainly declare their origin and 

 meaning in various ways. There are beetles belonging 

 to closely allied species, or even to the same identical 

 species, which have either full-sized and perfect wings, 

 or mere rudiments of membrane, which not rarely lie 

 under wing-covers firmly soldered together; and in these 

 cases it is impossible to doubt, that the rudiments repre- 

 sent wings. Eudimentary organs sometimes retain their 

 potentiality: this occasionally occurs with the mam- 



